Walls drying out after re-plastering, or too much water?

[HerOutdoors]

Hello!
I'm new to this forum - a friend suggested it'd be helpful. I am currently renovating a badly neglected old house. We know there are multiple issues around drainage on the east-facing end wall, There's a lot of cement render and missing lime render, and spalled brick, and the kitchen cabinets were going damp at the back. We removed them, scraped off the (mouldy!) layers of paper, and got back to sound lime plaster that was dry. It was in good condition bar a few cracks/dints, so I just skimmed it with more lime. I painted it with breathable paint.
We're now finding (a couple of weeks out), that the paint has dried perfectly fine. But, when it is raining or the temperature drops, the walls darken with damp. Sometimes there's even water coming out of them. They always dry out again within hours, and there's no sign of mould or mildew. Is this just the wall drying out? I am hoping once we get lime render back onto the outside wall, it'll be better?

Thanks!

 

[Feltwell]

It takes a long time for a wall to dry out, the old rule of thumb was a month for every inch thickness of wall, but of course it'll vary depending on how damp it is. What you're seeing could be a bit of surface condensation forming on a wall that is cold and damp further in - that would make sense with it happening when the weather is cold and / or damp. You've done the right thing on the inside, I think now it's just a case of getting the outside sorted as you say, then patience! That's presuming of course that no other factors are involved - leaky gutters above, bad roof, too high ground levels etc.

 

[HerOutdoors]

Thank you, that's a really helpful rule of thumb. And yes - I'm a bit worried there are other factors involved (my hunch is there are), but I'm glad to know it's not necessarily a bad sign if it's really visible when the damp comes through. Much appreciated!

 

[Cassie]

I know nothing, and the elders of this parish have been an enormous help to me. Feltwell told me that even though I thought my bricks were drying out, it was in fact just the surface drying and the saturated wall was going to take a lot longer, as per his advice above. What’s happening now after a few weeks are salts-lots of them coming out of the bricks that have been sodden for years. I don’t know, maybe that could be contributing?

 

[Feltwell]

Now salts coming out is a great sign! The moisture inside the bricks is evaporating off at the surface, leaving the dissolved salts behind on the surface. Keep brushing the worst of them off with a stiff dry brush, as they can be hydroscopic and attract moisture. You don't always get salts appearing of course, depends what was in the plaster and bricks.

 

[Zebra]

I hate to be the voice of doom.....but this situation sounds very familiar..... are the walls brick underneath the render? And how old is the house?